The present invention generally relates to service management systems and process control systems for intelligent network systems, and more particularly to a service management system and a process control system which controls process contentions in an intelligent network system.
Conventionally, there are intelligent network systems such as a Number Portability Service (NPS) which enables the use of the same telephone number even if a setup position of a telephone set is moved, and an Account Code Service (ACS).
FIG. 1 is a system block diagram showing the system structure of a conventional intelligent network system. In FIG. 1, a plurality of Service Switching Points (SSPs) 10.sub.1 through 10.sub.4 which make service inquiries and a Service Control Point (SCP) 12 are coupled via a common line signal network 16. A Service Management System (SMS) 18 manages a database of the SCP 12, and is coupled to a plurality of terminals 20.sub.1 through 20.sub.n.
In the conventional intelligent network system, the SMS 18 only controls the database of the single SCP 12, and the process contention control carried out by the SMS 18 is simple, such as checking the contention among operations. In addition, no special consideration is given as to the state of the load on the intelligent network system when carrying out an operation. Hence, when the load on the intelligent network system is large, the operator who operates the terminal restricted the operation by not executing the operation depending on the operator's judgement. However, it is difficult to rely on the operator to monitor the state of the load on the intelligent network system with respect to the operation which is periodically started, thereby causing the load on the intelligent network system to further increase even though the load is already large.
On the other hand, an Automatic Call Gapping (ACG) is prescribed by the ITU-T Recommendations as a mechanism for automatically reducing the load on the SCP in the intelligent network system. According to the ACG function, information such as gap duration and interval is transmitted to the SSP when the load on the SCP is excessively large, and the SSP restricts the'services depending on the received information and reduces service inquiries to the SCP, so that the load on the SCP is reduced.
Indeed, the load on the SCP changes proportionally to the amount of service inquiries from the SSP, and thus, the overload state of the SCP can be avoided by adjusting the amount of the service inquiries. However, in the intelligent network system which uses a general central processing unit (CPU) as the SCP, not only the amount of the service inquiries, but also maintenance operation application may cause the overload of the SCP. In this case, if the ACG function is activated as a means for reducing the load on the SCP, there is a problem in that the maintenance operation application will cause undesirable effects on the services.